Excessive salt (sodium chloride) intake, influenced by the strong preference or appetite for the salty taste, is an important factor in the development of hypertension in humans. The preference for the taste of salt represents more than an inherent liking but also the influence of experience. We have demonstrated recently that high salt intake during prenatal and early postnatal life is associated with increased salt preferences and elevated blood pressure levels in adult rats. This is a finding with important implications not only of salt intake and hypertension but also of the role of early nutrition on adult health. The proposed research will be directed at clarifying the relationship between the increased salt preference and elevated blood pressure levels due to early experience. Normotensive rats will be raised on diets that differ only in sodium chloride concentration. Then the animals' blood pressures and salt preference will be examined systematically to characterize their temporal relationship. Another goal is to determine the physiological mechanisms which underlie changes in salt intake. For example, increases in salt intake may be mediated by changes in gustatory sensitivity. Neurophysiological responses of gustatory neurons to sodium and nonsodium solutions will be recorded from rats that have been raised on diets differing in salt concentration. In addition, to determine whether early salt intake is associated with a mtabolic modification, electrolyte concentrations in the plasma and urine of the experimental animals will also be assessed. A final objective is to ascertain the relative importance of experience and genetic factors in the development of salt preference and hypertension. Therefore we will subject spontaneously hypertensive rats, a widely used animal model of experimental hypertension, to the smae experimental treatments described for normotensive control rats. This data will help increase our understanding of genetic-environmental interactions in the development of hypertension.